Re: Water and gum coating

"... what I'm more interested in in the
future is not the exact structure of chromium in gum, but a printing
process that does not use silver or chromium or iron, and the process
that may be very slow but can use visible light instead of UV
light. Is there anything like that now? (kinda like the sensitizer for
screen printing but not quite)"

I guess a great many photopolymer system exist that may work in that sense.
E.g. acrylamide systems achieve speed levels somewhere between silver
halides and dichromates. In addition they can be spectrally sensitized:
erythrosin, rose bengal etc. for green and methylene blue for red exposures.
Adding PVA to the solution will provide sufficient protection from oxygen
(which inhibites radical polymerization).

You may try the formula introduced by Suzan Martin:

"PVA (10% solution in water.).........17.5ml
Triethanolamine...................................2ml
Erythrosine B (0.11g/100ml water).......4ml

Acrylamide.........................................0.6 g
Methylenediacrylamide ........................0.2g
Water remainder to make above up to 25ml

For red sensitive material use 4mg (or 4ml) of methylene blue dye (water
soluble, useful solution is 1g/1000ml) instead of the 4ml of Erythrosine B
solution."

Martin

----- Original Message -----
From: "Ryuji Suzuki" <rs@silvergrain.org>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, May 20, 2004 12:40 AM
Subject: Re: Water and gum coating

> From: "Christina Z. Anderson" <zphoto@uslink.net>
> Subject: Re: Water and gum coating
> Date: Tue, 18 May 2004 20:42:38 -0500
>
> > The myth is in all gum books, passed along for generations--e.g.
coat
> > paper in room light as it is not sensitive until dry, but dry it in the
> > dark, blah blah blah.
>
> Well, I was more interested in the rationale behind that thought, but
> that's ok for now.
>
> > I mean, I coat *and* dry my paper in room light, so it doesn't make
> > any difference to me one way or another, but all you have to do is
> > stick a wet coated paper under UV light for a brief moment to see
> > that it immediately exposes.
>
> I see, but the the relation between wet sensitivity and dry
> sensitivity varies with the pH... so, it is possible that in some
> cases wet material is much less sensitive (in relation to dry
> sensitivity) than what you have. I think some material was purposely
> formulated to get that effect. It might be that the words got
> separated from substance and spread around... it happens in silver
> gelatin darkroom books as well.
>
> Anyway, after all these stuff, what I'm more interested in in the
> future is not the exact structure of chromium in gum, but a printing
> process that does not use silver or chromium or iron, and the process
> that may be very slow but can use visible light instead of UV
> light. Is there anything like that now? (kinda like the sensitizer for
> screen printing but not quite)
>
> --
> Ryuji Suzuki
> "You have to realize that junk is not the problem in and of itself.
> Junk is the symptom, not the problem."
> (Bob Dylan 1971; source: No Direction Home by Robert Shelton)
Received on Thu May 20 02:04:00 2004